The present invention relates to a rotatable-drum laundry drier, and to a method of controlling a rotatable-drum laundry drier to dry delicate laundry.
In particular, the present invention relates to a kind of rotatable-drum laundry drier comprising: a outer box casing; a cylindrical drum for housing the laundry to be dried, and which is arranged in axially rotating manner inside the casing to rotate about its longitudinal axis, directly facing a laundry loading and unloading opening formed in the front face of the casing; a door hinged to the front face of the casing to rotate to and from a rest position closing the opening in the front face of the casing to seal the casing and the drum; a hot-air generator designed to circulate inside the revolving drum, across a inner recirculating conduit, a stream of hot air with a low moisture content, and which flows through the revolving drum and over the laundry inside the drum to rapidly dry the laundry.
Such a rotatable-drum laundry drier further comprises: a transmission assembly that rotates the drum; a centrifugal fan which is located along the recirculating conduit and is designed to produce, inside the recirculating conduit, an airflow flowing through the drum; and a single electrical motor which drives both the centrifugal fan and the transmission assembly for rotating the revolving drum.
More specifically, the transmission assembly comprises an endless belt which passes around the outer periphery of the drum and around to the shaft of the electric motor, whereas the centrifugal fan is coupled to the electric motor shaft so as to rotate together with the drum.
As is known, drying delicate laundry, such as woolens or similar, in a rotatable-drum laundry drier of the type above disclosed, is a risky operation, on account of the known tendency of delicate laundry to felt and/or undergo other damage. Both substantially depend on a combination of two critical drying factors, such as drying air temperature and surface rubbing of the laundry against the inner wall of the casing or of the drum as it rotates.
To reduce rubbing of the laundry, a rotatable-drum laundry drier has been devised whereby, substantially, the drum is controlled to reach a prefixed high rotation speed during the drying cycle, so that delicate laundry is pressed by centrifugal force against the inner wall of the drum, to which it adheres and is prevented from sliding/tumbling inside the drum. A rotatable-drum laundry of this sort is described, for example, in EP2014822 filed by the Applicant.
Unfortunately, when the electric motor rotates at high rotation speed, the centrifugal fan rotates together with the drum at a high speed and blows a very high air flow rate inside the drum, which tends to separate the laundry from the inner drum surface, causing a gradual movement of the laundry itself towards the laundry opening. Since in the above rotatable-drum laundry drier, the cylindrical drum is shaped so as to present two opposite opened sides then, during the high rotation speed, the laundry is pushed against an inner flange fixed to the casing around the laundry opening, wherein the laundry is subjected to damages and shrinkage.